Histamine-induced mucociliary dysfunction and otitis media with effusion

Effects of histamine on ciliary beat frequency of ciliated cells from guinea pigs nasal mucosa

We aimed to investigate the effect of histamine on ciliary beat frequency (CBF) through combining high-speed digital microscopy and patch-clamp technology. Ciliated cells were obtained from septum and turbinate of 90-120-day-old healthy male guinea pigs. Tight seal was formed by applying negative pressure on the glass electrode after the drawing and pushing progress. Then, we enrolled high-speed digital microscopy to measure CBF before and after treatment with histamine of different concentrations ranging from 10(-6) to 10(-1) mol/L in Hank's solution and D-Hank's solution as well as after administrating adenosine triphosphate. One-way ANOVA, Student's t test or Kruskal-Wallis test was used for statistical comparisons. Glass electrode fix up ciliated cell is available at tip diameter of 2-5 μm and negative pressure of 10-20 cmH2O column. The baseline CBF in Hank's solution was higher than in D-Hank's solution. Treatment with 10(-6)-l0(-3) mol/L histamine of concentrations can stimulate a rise of CBF. Nevertheless, CBF in all groups decreased to baseline CBF within 20 min. Generally, 10(-2) mol/L histamine can stimulate a rise of CBF; meanwhile, the high concentration of histamine killed 50% ciliated cell. Histamine at 10(-1) mol/L killed all ciliated cells. Ciliary beating activity decreased in Ca(2+)-free solution. Moreover, adenosine triphosphate could increase CBF effectively after the stimulation effect of histamine. We construct an effective technology integrating patch-clamp technique with CBF measurements on ciliated cells. Extracellular histamine stimulation could increase CBF effectively.

Can Helicobacter pylori cause inflammation in the middle ear?

OBJECTIVES

To investigate whether Helicobacter pylori causes inflammation in the normal middle ear and in the middle ear with effusion.

METHODS

Sixteen adult New Zealand white rabbits were divided into two gropus equally. Group I was representing histamine-induced middle ear inflammation and Group II was representing normal middle ear. While H. pylori was inoculated in the right ears, physiologic saline was inoculated in the left ears of the rabbits in both groups. Results were evaluated clinically, histopathologically and microbiologically. Fisher's exact test was used for statistical analysis.

RESULTS

In Group I, clinical scores of the inflammation in the right ears were higher than the left ears scores at the 7th day. Histopathological scores of the inflammation in the right ears were higher than the left ears scores at the 7th day. Also, H. pylori was isolated in 6 of the 8 right ears of the rabbits. In Group II, while clinical scores of the inflammation in the right ears scores were higher than the left ears scores at the 7th day, histopathological scores were not significantly different between both ears. Also, no H. pylori was isolated in right ears of the rabbits.

CONCLUSIONS

Effusion in the middle ear induced by histamine is an appropriate medium for H. pylori reproduction and it also aggravates the inflammation process. In contrary, H. pylori did not cause inflammation in the normal middle ear. We suggest that H. pylori does not play a role in the etiology of otitis media with effusion alone, but it contributes to the inflammation process in the presence of an effusion.

The role of inflammatory mediators in the pathogenesis of otitis media and sequelae

This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K⁺ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued.

Action of histamine on eustachian tube function

INTRODUCTION

The role of allergy in eustachian tube dysfunction is controversial. In this study, allergy was simulated by exposure to histamine, and eustachian tube function testing was performed in an experimental rat model.

METHODS

Ventilatory function was assessed by measuring passive opening and closing pressures of the eustachian tube after challenge with either transtympanic or intranasal histamine. The mucociliary clearance time of the tubotympanum was assessed by observing dye transport from the middle ear to the nasopharynx after challenge with either transtympanic histamine or control solution.

RESULTS

There was a statistically significant increase in passive opening and closing pressures with transtympanic histamine versus intranasal histamine. In addition, mucociliary clearance times of the tubotympanum after transtympanic histamine showed a statistically significant increase when compared with those after transtympanic control solution.

CONCLUSIONS

Transtympanic histamine exposure causes eustachian tube dysfunction in the rat by increasing passive opening and closing pressures of the eustachian tube and impairing mucociliary clearance time.

A new rat model of otitis media caused by Streptococcus pneumoniae: conditions and application in immunization protocols

Streptococcus pneumoniae (pneumococcus [Pn]) can be cultured from up to 50% of acute otitis media (AOM) effusions, and these bacteria are the most common cause of AOM-related complications. With the recent advent of antibiotic-resistant Pn strains, treatment of Pn infections may meet with serious difficulties. Prevention through vaccination, notably for the four most common occurring Pn serotypes in humans (i.e., Pn 6B, Pn 14, Pn 19F, and Pn 23F), is a helpful alternative. Testing of vaccine efficacy should occur in an appropriate animal AOM model, which is presented here. The four involved Pn serotypes are not pathogenic to the rat, which was chosen as the experimental animal for practical reasons. To induce a natural infection (i.e., ascending through the eustachian tube), the mucociliary clearance of the eustachian tube was impaired by infusing histamine into the tympanic cavity on 2 consecutive days before intranasal inoculation of the bacteria. With this simple protocol, high and reproducible infection rates, as determined with bacterial cultures, of Pn-induced AOM (approximately 70%) with the two major Pn serotypes 14 and 19F (Pn 14 and Pn 19F) were obtained, whereas lower infection rates (25 to 50%) with Pn 6B and Pn 23F were obtained. In this model, intranasal priming with pneumococci, as well as subcutaneous vaccination with Pn 14 tetanus toxoid-conjugated polysaccharide, induced a protective effect against the induction of otitis media with these bacteria. This shows that immunity to Pn 14 AOM can be induced by both mucosal and systemic presentations of antigen. In conclusion, we have developed an animal model for Pn-induced AOM, which is suitable for the evaluation of the protecting effect of immunization.

Kinin and histamine stimulate Cl- secretion in gerbil middle ear epithelium: connection to otitis media

The effects of bradykinin (BK) and histamine on transepithelial ion transport in primary cultures of gerbil middle ear epithelium were investigated. Lysyl-bradykinin (lys-BK) elicited a transient increase in short-circuit current (I(sc)) when added to apical or basolateral surfaces. Lys-BK had a larger effect than BK or des-arg9-BK on both epithelial surfaces. Histamine induced a transient increase in I(sc) only when added to the basolateral surface. Mepyramine, an H1 histamine antagonist, greatly reduced the histamine-induced I(sc). The H2 and H3 histamine antagonists were both ineffective for inhibiting the I(sc) responses to histamine. Diphenylamine-2-carboxylate or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, Cl- channel blockers, significantly blocked the I(sc) responses to lys-BK or histamine. The Ca2+-mobilizing action of lys-BK and histamine was also investigated in single middle ear epithelial cells. BK and histamine induced an increase in the intracellular Ca2+ concentration. 1,2-Bis-(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, a calcium chelator, greatly reduced the increase in the I(sc) responses to lys-BK or histamine. These data indicate that BK and histamine activate intracellular Ca2+-dependent mechanisms, leading to apical Cl- secretion in the cultured gerbil middle ear epithelium via B2 BK receptors and H1 histamine receptors.

The herbal medicine, sairei-to, enhances the mucociliary activity of the tubotympanum in the healthy guinea pig

Mucociliary dysfunction in the tubotympanum is deeply reflected in the clinical manifestations of otitis media with effusion (OME), and clinical application of pharmacological agents with ciliostimulatory action might therefore enhance the mucociliary clearance function of the tubotympanum to more effectively eliminate middle ear effusions to the pharynx. A herbal medicine, sairei-to, enhances the in vitro ciliary activity of the middle ear during culture. However, this ciliostimulatory effect is not always applicable to the mucociliary system in situ, which may be deteriorated following oral administration of sairei-to. The present study therefore aimed at investigating the in vivo effect of sairei-to on the mucociliary system in the tubotympanum of the guinea pig. Thirty healthy guinea pigs were used. Ten animals were treated with oral administration of physiologic saline solution for 14 successive days. The remaining animals were treated with oral administration of 120 or 600 mg/kg body weight of sairei-to for 14 successive days. Each animal was used for examination of the ciliary activity and mucociliary clearance time of the tubotympanum, 24 h after the final treatment. No significant changes in either ciliary activity or mucociliary clearance time of the tubotympanum were observed upon administration of 120 mg/kg of sairei-to, which was equivalent to the clinical human dosage. By contrast, oral administration of 600 mg/kg of sairei-to significantly enhanced the ciliary activity, but failed to significantly accelerate mucociliary clearance in the tubotympanum, although the mean value of the clearance time became shorter. Therefore, our results suggest that sairei-to to some extent stimulates the function of the mucociliary system. In conclusion, the herbal medicine, sairei-to, might be useful in the treatment of OME, and preventive administration of this drug may be a new therapy in the treatment of recurrent OME.

The herbal medicine, sairei-to, prevents endotoxin-induced otitis media with effusion in the guinea pig

With current pharmacotherapy, otitis media with effusion (OME) is often recurrent and even develops to become chronic. There is now considerable experimental and clinical evidence that the cilia in the tubotympanum play an important part in the prevention of OME. A herbal medicine, sairei-to, has been shown to stimulate the ciliary activity in vitro, and oral administration of the medicine also stimulated the ciliary activity in the tubotympanum rather than physiological states. This study was designed to investigate whether oral administration of sairei-to could prevent experimental OME in the guinea pig. A total of 120 guinea pigs were used. The control group was treated with intratympanic injection of 0.1 ml of physiologic saline solution. The saline-control group was treated with oral administration of physiologic saline solution for 14 successive days. The low-dosage group and the high-dosage group were treated with oral administration of 120 and 600 mg/kg of sairei-to for 14 successive days, respectively. The saline-control group, the low-dosage group and the high-dosage group were then treated with intratympanic injection of 0.1 ml of lipopolysaccharide solution (100 micrograms/ml) derived from Klebsiella pneumoniae. All 10 animals from the 4 groups were sacrificed 1, 3, and 7 days after the intratympanic injection, to examine ciliary activity, mucociliary clearance time, and mucosal pathology of the tubotympanum. The saline-control group exhibited middle ear effusions and pathologies similar to human OME. The incidence of middle ear effusions in the low-dosage and the high-dosage groups was somewhat reduced compared with the saline-control group. The ciliary activity in the tubotympanum was significantly reduced in the saline-control and low-dosage groups compared with the normal-control group. By contrast, the magnitude of reduction in ciliary activity was much smaller in the high-dosage group. The ciliary activity especially in the Eustachian tube and the middle ear close to the tympanic orifice at 3 and 7 days in the high-dosage group was not significantly different from that in the normal-control group. Mucociliary clearance time in the high-dosage group was not different from that in the normal-control group throughout the observation period. The groups treated with sairei-to, especially the high-dosage group, exhibited much milder pathological changes in the tubotympanum than did the saline-control group. In conclusion, clinical application of sairei-to could be an effective measure to prevent the occurrence of OME and also the recurrence of the disease, especially OME-prone individuals.

Roxythromycin prevents endotoxin-induced otitis media with effusion in the guinea pig

Pharmacological agents that can normalize or enhance the ciliary and mucociliary activity of the tubotympanum should also be able to break the vicious circle of chronic otitis media with effusion (OME). Roxythromycin (RXM) has been shown to enhance the ciliary activity in vitro and also stimulate the mucociliary activity in vivo and may therefore, when clinically applied, prevent not only occurrence but also recurrence of clinical OME. The present study was designed to discuss the possible preventive effect of RXM on endotoxin-induced OME in the guinea pig. A total of 120 guinea pigs were used. The normal control group was treated with intratympanic injection of 0.1 ml of physiologic saline solution. The saline-control group was treated with oral administration of physiologic saline solution for 14 successive days. The low-dosage group and the high-dosage group were treated with oral administration of 5 and 50 mg/kg of sairei-to for 14 successive days, respectively. Then, the saline-control group, the low-dosage group and the high-dosage group were treated with intratympanic injection of 0.1 ml of lipopolysaccharide solution (100 micrograms/ml) derived from Klebsiella pneumoniae. All 10 animals in the four groups were sacrificed 1, 3, and 7 days after the intratympanic injection, to examine ciliary activity, mucociliary clearance time, and mucosal pathology of the tubotympanum. The saline-control group exhibited middle ear effusions and pathologies similar to human OME. The incidence of middle ear effusions was significantly reduced in the low-dosage and high-dosage groups. Throughout the observation period, the ciliary activity in the tubotympanum was significantly reduced in the saline-control group as compared with that of the normal control group. By contrast, the ciliary activity in the low-dosage and high-dosage groups was not so reduced in the Eustachian tube and the middle ear close to the orifice. Mucociliary clearance time in the low-dosage and high-dosage groups was not different from that in the normal control group throughout the period. The tubotympanum in the saline-control group exhibited mucosal pathologies characteristic of OME in human. By contrast, the low-dosage and high-dosage groups exhibited much milder pathological changes in the tubotympanum than those in the saline-control group. In conclusion, clinical application of RXM could be an effective measure to prevent the occurrence of OME and also the recurrence of the disease, especially in OME-prone individuals.

Effects of human middle ear effusions on the mucociliary system of the tubotympanum in the guinea pig

Effusion fluid resulting from otitis media contains a variety of inflammatory substances. This middle ear effusion (MEE) may be itself affect the mucosa of the tubotympanum and contribute to chronicity of the condition. The present study was designed to elucidate in vitro and in vivo effects of MEEs on the mucosa of the guinea pig tubotympanum. The results obtained demonstrated that the ciliary activity of the eustachian tube was reduced in the presence of human MEEs. This activity decreased to approximately 80% in the presence of serous MEE at 48 h and was 60% after exposure to mucoid MEE. Intratympanic inoculation of human MEEs resulted in accumulation of a serous effusion in the tympanic cavity. Histologic study of the tubotympanum in inoculated animals demonstrated mucociliary dysfunction as well as a general inflammatory process and increased vascular permeability. This damage was more prominent following inoculation with the mucoid MEEs. The ciliary depression and inflammation found in the tubotympanum suggest that the pathologic nature of MEEs may be, at least partially, responsible for the chronicity of otitis media.